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The masses of the neutron-rich copper isotopes Cu75–79 are determined using the precision mass spectrometer ISOLTRAP at the CERN-ISOLDE facility. The trend from the new data differs significantly from that of previous results, offering a first accurate view of the mass surface adjacent to the Z=28, N=50 nuclide Ni78 and supporting a doubly magic character. The new masses compare very well with large-scale shell-model calculations that predict shape coexistence in a doubly magic Ni78 and a new island of inversion for Z

The copper isotope effect (63Cu vs.65Cu) on the relaxation rate of crystal-field excitations in the slightly underdoped high-temperature superconductor HoBa2Cu4O8 has been investigated by inelastic neutron scattering. For the 63Cu compound there is clear evidence for the opening of an electronic gap in the normal state at T * ≈ 160 K far above Tc = 79.0 K. Upon substitution of 63Cu by 65Cu, Tc decreases marginally to 78.6 K, whereas T * is increased to about 185 K. This large copper isotope shift ΔT * (Cu) = T * (65Cu) - T * (63Cu) ≈ 25 K - together with the corresponding oxygen isotope shift ΔT * (O) = T * (18O) - T * (16O) ≈ 50 K found in an earlier investigation - suggests that phonons or lattice fluctuations involving both the copper and the oxygen ions are important for the pairing mechanism in high-Tc materials.

We report the first confirmation of the predicted inversion between the pi2p3/2 and pi1f5/2 nuclear states in the nu(g)9/2 midshell. This was achieved at the ISOLDE facility, by using a combination of in-source laser spectroscopy and collinear laser spectroscopy on the ground states of 71,73,75Cu, which measured the nuclear spin and magnetic moments. The obtained values are mu(71Cu)=+2.2747(8)mu(N), mu(73Cu)=+1.7426(8)mu(N), and mu(75Cu)=+1.0062(13)mu(N) corresponding to spins I=3/2 for 71,73Cu and I=5/2 for 75Cu. The results are in fair agreement with large-scale shell-model calculations.

For the first time, in-gas-cell laser spectroscopy study of the $^{57,59,63,65}\mathrm{Cu}$ isotopes has been performed using the 244.164 nm optical transition from the atomic ground state of copper. The nuclear magnetic dipole moments for $^{57,59,65}\mathrm{Cu}$ relative to that of $^{63}\mathrm{Cu}$ have been extracted. The new value for $^{57}\mathrm{Cu}$ of $\ensuremath{\mu}(^{57}\mathrm{Cu})=+2.582(7){\ensuremath{\mu}}_{N}$ is in strong disagreement with the previous literature value but in good agreement with recent theoretical and systematic predictions.

Spin dynamics at planar sites in oxygen-deficient ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6+\mathrm{x}}$ have been investigated by nuclear spin-lattice relaxation measurements using $^{63}$,65Cu nuclear quadrupole resonance and $^{89}\mathrm{Y}$ NMR. A sharp decrease of $^{63}\mathrm{Cu}$ nuclear relaxation below 100 K in ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.7}$ suggests the possible onset of spin pairing in individual planes well above the transition to three-dimensional bulk superconductivity. Comparison of the relaxation rates for the 60-K superconductor ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.7}$ with those of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7.0}$ in the range 100--300 K shows that the planar Cu(2) spin dynamics are strongly affected by changes in carrier concentration.

In the investigation of the elastic scattering of deuterons by separated isotopes of nickel and copper, it was found that the spectra of Cu/sup 63/ and Cu/ suup 65/ show a group in the neighborhood of 1.3 Mev. From a graph of relative intensity plotted against excitation energy it is apparent that the resolution is such that the levels in the copper isotopes could not be well resolved. It is clear both from location and width of the peak that it is due to more than one of the five levels around 1.3 Mev. (AC.)